NV_pixel_data_range performance

I’ve tried the PixPerf test program from Cass’s website with the following disappointing results:

No PDR: 10.972647 Mpixels/sec
With PDR: 11.913567 Mpixels/sec

My system is: GeForce2MX (Det 43.35), Win2k, AMD 1.2GHz

Any suggestions to improve the performance a little bit?

Hampel